/*
Copyright 2020 The Flux authors

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package canary

import (
	"context"
	"fmt"

	"go.uber.org/zap"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime/schema"
	"k8s.io/client-go/kubernetes"

	flaggerv1 "github.com/fluxcd/flagger/pkg/apis/flagger/v1beta1"
	clientset "github.com/fluxcd/flagger/pkg/client/clientset/versioned"
)

// ServiceController is managing the operations for Kubernetes service kind
type ServiceController struct {
	kubeClient    kubernetes.Interface
	flaggerClient clientset.Interface
	logger        *zap.SugaredLogger
}

// SetStatusFailedChecks updates the canary failed checks counter
func (c *ServiceController) SetStatusFailedChecks(cd *flaggerv1.Canary, val int) error {
	return setStatusFailedChecks(c.flaggerClient, cd, val)
}

// SetStatusWeight updates the canary status weight value
func (c *ServiceController) SetStatusWeight(cd *flaggerv1.Canary, val int) error {
	return setStatusWeight(c.flaggerClient, cd, val)
}

// SetStatusIterations updates the canary status iterations value
func (c *ServiceController) SetStatusIterations(cd *flaggerv1.Canary, val int) error {
	return setStatusIterations(c.flaggerClient, cd, val)
}

// SetStatusPhase updates the canary status phase
func (c *ServiceController) SetStatusPhase(cd *flaggerv1.Canary, phase flaggerv1.CanaryPhase) error {
	return setStatusPhase(c.flaggerClient, cd, phase)
}

// GetMetadata returns the pod label selector, label value and svc ports
func (c *ServiceController) GetMetadata(_ *flaggerv1.Canary) (string, string, map[string]int32, error) {
	return "", "", nil, nil
}

// Initialize creates or updates the primary and canary services to prepare for the canary release process targeted on the K8s service
func (c *ServiceController) Initialize(cd *flaggerv1.Canary) (err error) {
	targetName := cd.Spec.TargetRef.Name
	primaryName := fmt.Sprintf("%s-primary", targetName)
	canaryName := fmt.Sprintf("%s-canary", targetName)

	svc, err := c.kubeClient.CoreV1().Services(cd.Namespace).Get(context.TODO(), targetName, metav1.GetOptions{})
	if err != nil {
		return fmt.Errorf("service %s.%s get query error: %w", primaryName, cd.Namespace, err)
	}

	if err = c.reconcileCanaryService(cd, canaryName, svc); err != nil {
		return fmt.Errorf("reconcileCanaryService failed: %w", err)
	}

	if err = c.reconcilePrimaryService(cd, primaryName, svc); err != nil {
		return fmt.Errorf("reconcilePrimaryService failed: %w", err)
	}

	return nil
}

func (c *ServiceController) reconcileCanaryService(canary *flaggerv1.Canary, name string, src *corev1.Service) error {
	current, err := c.kubeClient.CoreV1().Services(canary.Namespace).Get(context.TODO(), name, metav1.GetOptions{})
	if errors.IsNotFound(err) {
		return c.createService(canary, name, src)
	} else if err != nil {
		return fmt.Errorf("service %s.%s get query error: %w", name, canary.Namespace, err)
	}

	ns := buildService(canary, name, src)

	if ns.Spec.Type == "ClusterIP" {
		// We can't change this immutable field
		ns.Spec.ClusterIP = current.Spec.ClusterIP
	}

	// We can't change this immutable field
	ns.ObjectMeta.UID = current.ObjectMeta.UID

	ns.ObjectMeta.ResourceVersion = current.ObjectMeta.ResourceVersion

	_, err = c.kubeClient.CoreV1().Services(canary.Namespace).Update(context.TODO(), ns, metav1.UpdateOptions{})
	if err != nil {
		return fmt.Errorf("updating service %s.%s failed: %w", name, canary.Namespace, err)
	}

	c.logger.With("canary", fmt.Sprintf("%s.%s", canary.Name, canary.Namespace)).
		Infof("Service %s.%s updated", ns.GetName(), canary.Namespace)
	return nil
}

func (c *ServiceController) reconcilePrimaryService(canary *flaggerv1.Canary, name string, src *corev1.Service) error {
	_, err := c.kubeClient.CoreV1().Services(canary.Namespace).Get(context.TODO(), name, metav1.GetOptions{})
	if errors.IsNotFound(err) {
		return c.createService(canary, name, src)
	} else if err != nil {
		return fmt.Errorf("service %s.%s get query error: %w", name, canary.Namespace, err)
	}
	return nil
}

func (c *ServiceController) createService(canary *flaggerv1.Canary, name string, src *corev1.Service) error {
	svc := buildService(canary, name, src)

	if svc.Spec.Type == "ClusterIP" {
		// Reset and let K8s assign the IP. Otherwise we get an error due to the IP is already assigned
		svc.Spec.ClusterIP = ""
	}

	// Let K8s set this. Otherwise K8s API complains with "resourceVersion should not be set on objects to be created"
	svc.ObjectMeta.ResourceVersion = ""

	_, err := c.kubeClient.CoreV1().Services(canary.Namespace).Create(context.TODO(), svc, metav1.CreateOptions{})
	if err != nil {
		return fmt.Errorf("creating service %s.%s query error: %w", canary.Name, canary.Namespace, err)
	}

	c.logger.With("canary", fmt.Sprintf("%s.%s", canary.Name, canary.Namespace)).
		Infof("Service %s.%s created", svc.GetName(), canary.Namespace)
	return nil
}

func buildService(canary *flaggerv1.Canary, name string, src *corev1.Service) *corev1.Service {
	svc := src.DeepCopy()
	svc.ObjectMeta.Name = name
	svc.ObjectMeta.Namespace = canary.Namespace
	svc.ObjectMeta.OwnerReferences = []metav1.OwnerReference{
		*metav1.NewControllerRef(canary, schema.GroupVersionKind{
			Group:   flaggerv1.SchemeGroupVersion.Group,
			Version: flaggerv1.SchemeGroupVersion.Version,
			Kind:    flaggerv1.CanaryKind,
		}),
	}
	_, exists := svc.ObjectMeta.Annotations["kubectl.kubernetes.io/last-applied-configuration"]
	if exists {
		// Leaving this results in updates from flagger to this svc never succeed due to resourceVersion mismatch:
		//   Operation cannot be fulfilled on services "mysvc-canary": the object has been modified; please apply your changes to the latest version and try again
		delete(svc.ObjectMeta.Annotations, "kubectl.kubernetes.io/last-applied-configuration")
	}
	return svc
}

// Promote copies target's spec from canary to primary
func (c *ServiceController) Promote(cd *flaggerv1.Canary) error {
	targetName := cd.Spec.TargetRef.Name
	primaryName := fmt.Sprintf("%s-primary", targetName)

	canary, err := c.kubeClient.CoreV1().Services(cd.Namespace).Get(context.TODO(), targetName, metav1.GetOptions{})
	if err != nil {
		return fmt.Errorf("service %s.%s get query error: %w", targetName, cd.Namespace, err)
	}

	primary, err := c.kubeClient.CoreV1().Services(cd.Namespace).Get(context.TODO(), primaryName, metav1.GetOptions{})
	if err != nil {
		return fmt.Errorf("service %s.%s get query error: %w", primaryName, cd.Namespace, err)
	}

	primaryCopy := canary.DeepCopy()
	primaryCopy.ObjectMeta.Name = primary.ObjectMeta.Name
	if primaryCopy.Spec.Type == "ClusterIP" {
		primaryCopy.Spec.ClusterIP = primary.Spec.ClusterIP
	}
	primaryCopy.ObjectMeta.ResourceVersion = primary.ObjectMeta.ResourceVersion
	primaryCopy.ObjectMeta.UID = primary.ObjectMeta.UID

	// apply update
	_, err = c.kubeClient.CoreV1().Services(cd.Namespace).Update(context.TODO(), primaryCopy, metav1.UpdateOptions{})
	if err != nil {
		return fmt.Errorf("updating service %s.%s spec failed: %w",
			primaryCopy.GetName(), primaryCopy.Namespace, err)
	}

	return nil
}

// HasServiceChanged returns true if the canary service spec has changed
func (c *ServiceController) HasTargetChanged(cd *flaggerv1.Canary) (bool, error) {
	targetName := cd.Spec.TargetRef.Name
	canary, err := c.kubeClient.CoreV1().Services(cd.Namespace).Get(context.TODO(), targetName, metav1.GetOptions{})
	if err != nil {
		return false, fmt.Errorf("service %s.%s get query error: %w", targetName, cd.Namespace, err)
	}
	return hasSpecChanged(cd, canary.Spec)
}

// Scale sets the canary deployment replicas
func (c *ServiceController) ScaleToZero(_ *flaggerv1.Canary) error {
	return nil
}

func (c *ServiceController) ScaleFromZero(_ *flaggerv1.Canary) error {
	return nil
}

func (c *ServiceController) SyncStatus(cd *flaggerv1.Canary, status flaggerv1.CanaryStatus) error {
	dep, err := c.kubeClient.CoreV1().Services(cd.Namespace).Get(context.TODO(), cd.Spec.TargetRef.Name, metav1.GetOptions{})
	if err != nil {
		return fmt.Errorf("service %s.%s get query error: %w", cd.Spec.TargetRef.Name, cd.Namespace, err)
	}

	return syncCanaryStatus(c.flaggerClient, cd, status, dep.Spec, func(cdCopy *flaggerv1.Canary) {})
}

func (c *ServiceController) HaveDependenciesChanged(_ *flaggerv1.Canary) (bool, error) {
	return false, nil
}

func (c *ServiceController) IsPrimaryReady(_ *flaggerv1.Canary) error {
	return nil
}

func (c *ServiceController) IsCanaryReady(_ *flaggerv1.Canary) (bool, error) {
	return true, nil
}

func (c *ServiceController) Finalize(_ *flaggerv1.Canary) error {
	return nil
}
